Toner unit for photoelectrostatic reproduction equipment



1957 w. v. SHEARER ETAL 3,

TONER UNIT FOR PHOTOELECTROSTATIC REPRODUCTION EQUIPMENT Original FiledApril 24, 1962 6 Sheets-Sheet 1 FIGURE 1 INVENTORS.

WALTER msuennm WILLIHM mes-:04, JR- amvow M-WHEELOCK, SR.

H'TI'GRNEY Dec. 19, 1967 w v, SHEARER ETAL 3,358,537

TONER UNIT FOR PHOTOELECTROSTATIC REPRODUCTION EQUIPMENT Original FiledApril 24, 1962 6 Sheets-Sheet 2 FIGURE 3 99 {4 5 83 m 43 43 NW 89 Il Q9/ 38 94 3 I 45 lhll I45 Wfd:?fln/ Inn- "951/ I 98 96 92 97 g 99 FIGURE2 INVENTORS. WALTER v. .SHEHRER WILL/HM R- BECK, JR.

HRNOLD M. WHEELOCK, 5R.

Dec. 19, 1967 w. v. SHEARER ETAL 3,358,637

TONER UNIT FOR PHOTOELECTROSTATIC REPRODUCTION EQUIPMENT Original FiledApril 24, 1962 6 Sheets-Sheet I5 lNVENTORS' F/fl/PE 4 WRLTER v. aye/M52WILL/HM R. BECK, J72 nmvow M. wHEELac/g 52.

Dec. 19, 1967 w v. SHEARER ETAL 3,358,637

TONER UNIT FOR PHOTOELECTROSTATIC REPRODUCTION EQUIPMENT Original FiledApril 24, 1962 6 Sheets-Sheet 4 F/GURE 5' INVENTORS, wmrerz male/9126AwILunM R- BECK, JR. nrzuow M. wusaocmsn.

GM; a 'kwmrw H7TORNEY Dec. 19, 1967 W. V- SHEARER ETAL Original FiledApril 24, 1962 INVENTORS. WQLTEQ V. SHEHRER WILL/HM l2. 6Ec1 ,J72.HRNOLD M. wHEEL00 ,5/2. m. mmcs g HTTORNEY United States Patent3,358,637 Patented Dec. 19, 1957 3,358,637 TONER UNIT FORPHOTOELECTROSTATIC REPRODUCTION EQUIPMENT Walter V. Shearer, Longmeadow,William R. Beck, Jr., Wilbraham, and Arnold M. Wheelock, Sr., Southwick,Mass., assignors to The Plastic Coating Corporation Original applicationApr. 24, 1962, Ser. No. 189,758, now Patent No. 3,180,239. Divided andthis application Dec. 23, 1964, Ser. No. 420,514

11 Claims. (Cl. 118-7) ABSTRACT OF THE DISCLOSURE Apparatus is disclosedfor applying powdered solid resinous toner to the surface of a copysheet which has an electrostatic image carried by a photoelectrostaticcoating thereon. The apparatus includes a stationary cylindrical core ofnonmagnetic material which core has a plurality of longitudinal groovescountersunk in its cylindrical surface at spaced intervals around itscircumference in which grooves strips of permanently magnetic materialare positioned. A rotatable cylindrical core or shell of nonmagneticmaterial is disposed about the stationary core. The apparatus includes atwo compartment tray for containing a body of toner mix in contact withthe lower part of the rotatable cylinder. The apparatus also includes adoctor blade disposed along the length of the rotatable core or shell,spaced uniformly from the surface of the shell and at a location atwhich the surface of the rotatable shell or cylinder is moved in anupwardly direction. One embodiment of the apparatus disclosed includes ameans for adjusting the circumferential position of the stationarycylindrical core and for locking it in its adjusted position. Theapparatus also includes rotatable stirrers in at least one of thecompartments of the tray foruniformly mixing the toner mix prior to itsbeing picked up by the rotatable cylinder or shell. A specificembodiment of the apparatus has a longitudinal slot connecting thecompartments of the two compartment tray and a grooved rotatablecylinder positioned within the second compartment of the tray adjacentthe longitudinal slot which closes the slot when stationary andtransfers fresh toner mixture from the second compartment into the firstcompartment when rotated. The disclosure also describes mechanical meansand electrical means for operating the toner apparatus in a specifiedmanner.

This application is a division of our copending application, Ser. No.189,758, filed Apr. 24, 1962, now Patent This invention relates to aunit for the application of a powdered resinous toner to a latentelectrostatic image formed in the photoelectrostatic reproduction of anoptical image to convert the latent image to a visible image.

The patent referred to above describes automatic apparatus for thephotoelectrostatic reproduction of images, which includes as anessential component the toner unit described and claimed by thisapplication. The usefulness of this toner unit is not limited to theparticular apparatus described by that application. It is well adaptedfor use with any apparatus for photoelectrostatic reproduction in whicha dry toning powder is used.

Briefly described, the process of photoelectrostatic reproduction inwhich the apparatus of this invention includes the following sequence ofessential steps. A sheet carrying a photoelectrostatic coating issubjected to a corona discharge to impose an electrostatic charge on thephotoelectrostatic coating on the sheet while the sheet is in darkness.The charged surface is then exposed to an optical image to be reproducedto produce a latent electrostatic image, which is then converted into avisible image by the application of a powdered solid or a liquid toner.The visible image produced by the use of a colored, powdered solid toneris made permanent by subjecting the image to heat to fuse the powderedtoner.

The toner unit in accordance with this invention applies a powderedsolid toner to the surface of a photoelectrostatic sheet carrying alatent electrostatic image while in darkness by at least one andpreferably two or more magnetic brushes. This unit is adapted to tone alatent electrostatic image on a photoelectrostatic sheet which is passedin contact with the magnetic brush or brushes of the unit and under abias shoe or shoes of the unit by a suitable conveyor system, with thelatent electrostatic image facing downwardly. The magnetic brush isformed on a cylinder of a non-magnetic material which rotates around astationary magnetic core, with the lower periphery of the non-magneticcylinder immersed in a mixture of a powdered, solid resinous toner and apowdered, magnetic solid such as powdered iron.

During the operation of this toner unit, the toner powder is deletedfrom the toner mixture since it selectively adheres to the latentelectrostatic image, while the magnetic particles of the mixture arelargely retained by the magnetic attraction by the stationary corewithin the rotating cylinder of non-magnetic material. This toner unitis provided with a mechanism by which toner powder or an enriched tonermixture is added to the body of toner mixture in which the non-magneticcylinder is rotating to replace the deleted toner powder. This mechanismcan be manually operated by remote control as may be desired or set tooperate automatically as will be fully explained hereinafter.

This toner unit comprises at least one cylindrical, stationary core of anon-magnetic material such as, for example, brass, which has lengthwisegrooves which are circumferentially spaced apart. Longitudinal,permanent magnets which may be of the plastic type are positioned withinthese grooves and substantially completely fill them to complete thecylindrical surface of the stationary core. Each of these permanentmagnets has a length equal to the width of the image area of the sheetto be toned. A pre ferred embodiment of this stationary core carries sixsuch longitudinal, permanent magnets at circumferentially, equallyspaced intervals around about 230 of its circumference. The rotaryposition of this core is capable of adjustment and of being firmly heldin the desired position with respect to the permanent magnets in itssurface. A rotatable, closely fitting, cylindrical sleeve of anonmagnetic material such as, for example, brass, is positioned aroundthis stationary core and has a means for its rotation around the core.The combination of a stationary core, the means for adjusting itscircumferential position, the outer sleeve and the means for itsrotation around the stationary core will be referred to hereinafter as amagnetic brush unit.

One of these magnetic brush units, and preferably two or more of them,are located within a longitudinal tray and spaced apart from its bottom.Also located within this tray below the magnetic brush unit or units isat least one, and preferably two or more, rotary stirrers or agitators.In the embodiment of this unit described hereinafter with reference tothe drawings, four such agitators are located below the two magneticbrush units with their axes parallel to the axes of the magneticbrushes. Each such agitator is provided with means for its rotationaround its longitudinal axis.

This magnetic toner unit is located in the apparatus with the axes ofits magnetic brush units at right angles to the direction of travel of asheet carried by a conveyor system.

When in use, this longitudinal tray is filled with a toner mix to alevel such that the lower surface of the magnetic brushes are immersedtherein. This toner mix is a mixture of a powdered resinous toner andparticles of a magnetic material such as, for example, iron, which iswell known to the art. The toner used for the direct production ofcopies is colored. That used for the production of a master which is toform a lithographic printing plate may or may not be colored, but ispreferably colored to facilitate the visual inspection of the image. Thetoner may be one which acquires a positive charge in the toner mixture.Such a toner tones the negative image areas of a latent electrostaticimage, and produces a positive copy. Alternatively, the toner may be onewhich assumes a negative charge. Such a toner is repelled by thenegative image areas and tones the background areas of a latentelectrostatic image and produces a negative reproduction of the originalimage.

The rotation of the cylindrical sleeve within the toner mix forms abrush on the portion of the outer surface of the rotating sleeve whichis adjacent the magnets of the stationary core. This magnetic brush iscontinuously formed and disrupted as the sleeve rotates, since it existsonly on the segment of the sleeve which is adjacent the permanentmagnets of the stationary core of the unit at any instant. The portionof the sleeve adjacent the circumferential portion of the core which hasno permanent magnets cannot retain magnetic brush.

Further, the end sections of. the sleeve adjacent the end sections ofthe core which do not carry the permanent magnets do not form a magneticbrush. The width of the magnetic brush which is formed is equal to thelengths of the permanent magnets of the core which, as already noted,are made equal in length to the width of the image area on the sheet tobe toned. Thus, the marginal areas of the sheet do not come into contactwith the magnetic toning brush or brushes, as the case may be, andhence, cannot pick up residual toner and become dirty in appearance,even if they carry a residual electrostatic charge.

A doctor blade may, if desired, be located adjacent the sleeve of themagnetic brush in a position to smooth the surface of the magnetic brushon the sleeve as it rotates to its uppermost position in which itcontacts a photoelectrostatic sheet passing over the toner unit. Thisdoctor blade corrects any tendency of the magnetic brush to have anon-uniform surface.

An insulating idler roll is positioned ahead of the toner brush unit,and another just after it. In a toner unit carrying tow or more magneticbrush units, an insulating idler roll is located between them. The upperperipheries of these idler rolls are just below the upper periphery orperipheries of the magnetic brush or brushes, as the case may be, whichare formed during the operation of this unit. The purpose of these rollsis to support the trailing end of the sheet being toned. The last ofthese insulating rolls, i.e., the one on the forwardly side of thetoning unit is particularly important in that it prevents the trailingend of the sheet being toned from flipping into the edge of he tonertray as it passes away from the toner unit and thereby avoids thetendency which it would otherwise have to knock the toner mix out of thetoner tray.

This continuous disruption of the magnetic brush or brushes, as the casemay be, in combination with the action of the agitators of the unit incontinually stirring the toner mix is an important feature of this tonerunit. It continually provides in the magnetic brush a toner mixcomposition which is substantially the same as that of the body of themix within the tray of the unit despite the continuing depletion of thetoner from the magnetic brush by deposition on the electrostatic imageof the photoelectrostatic sheets brought into contact with the brush orbrushes of the unit.

The mechanical stirrers for the toner mix described above provide aneffective means for stirring the toner mix to keep its compositionuniform. in an alternative embodiment of this toner unit which carriestwo or more magnetic brush units, the agitation of the toner mix isefifected by means of one or more magnetic stirrers located beneath andadjacent to the bottom of the tray of the toner unit which is preferablysinuous in contour across its length with parallel semi-cylindricaldepressions separated by a convex semi-cylindrical hump whichcorresponds to a concave semi-cylindrical depression in its lowersurface. The axis of each of the magnetic brush units is directly aboveand parallel to the axis of one of the semi-cylindrical depressions inthe bottom of the toner tray.

As an alternative to the above-described mechanical stirrers, one ormore magnetic stirrers may be used. The magnetic stirrer may be arotatable, magnetic cylinder comprised of a generally cylindrical bodyof a non-magnetic material carrying longitudinal strips of permanentlymagnetic material spaced apart around its circumference. This magneticcylinder is located beneath the bottom of the toner tray with its axisparallel to the axis of the hump in the bottom of the tray, as viewedfrom above, and parallel to the axes of the magnetic brush units. Inthis embodiment of the toner unit, the sleeves of the magnetic brushunits are preferably rotated in the same direction, while the magneticstirrer cylinder is provided with means for rotating it in the oppositedirection and is rotated in that direction when the unit is in use. Therotation of this magnetic stirrer cylinder causes the toner mix withinthe tray of the unit to move in the direction that the lower peripheriesof the sleeves of the magnetic brush units are moving with a resultantmixing of the material which falls from the sleeves upon the disruptionof the magnetic brushes with the body of the toner mixture within thetray.

The tray of the toner unit of this apparatus has a parti tion extendingdownwardly from its top which is parallel to the axis of the magneticbrush unit or units and adjacent thereto. The lower edge of thispartition is above a bottom surface of the tray leaving a slot whichopens into the section of the tray which carries the magnetic brushunits and agitators. A cylindrical member" which carries longitudinalslots or grooves on its surface is lo" cated adjacent this slot in aposition which substantially closes the slot. This partition and thegrooved cylinder form a compartment for toner or a toner mix whichcarries a toner content higher than that normally contained in theadjacent compartment in which the magnetic brush units are located. Therotation of the grooved cyl inder will convey the toner powder orenriched toner mix from this compartment into the adjacent compartmentin which the magnetic brush units operate. Thus, this grooved cylinderis adapted to function as a feeding and metering device for thereplenishment of toner from the toner mix in the adjacent compartment bythe magnetic brushes. This grooved cylinder will be referred tohereinafter as the toner feed cylinder and the compartment from which itfeeds toner or an enriched toner mix will be referred to as the tonersupply compartment.

This toner feed cylinder is provided with a means for" its rotation atperiodic intervals to replenish the toner in the adjacent compartment asit is depleted. This means for the rotation of the toner feed cylinderis controlled by the electrical system of the unit to feed toner atintervals determined by the number of copies which have been toned.Thus, it may be activated by the electrical system to feed anincreasement of toner each time ten copies have been toned. Thiselectrical control includes a series of switches or alternatively, amultiple contact rotary switch located at a position convenient to theoperator of the apparatus by which the periodicity of the ope ".titm ofthe toner feed cylinder can be determined. By the operation of theseswitches or the rotary switch, as the case may be, the operator of theapparatus may cause the toner feed cylinder to furnish an increasementof toner to the toner mix after, for example, the toning of ten copies,twenty copies, fifty copies, etc.

The periodicity with which the toner is replenished to the toner mix inthe operation of the apparatus is determined by the density of the imagewhich is being toned. An image which is relatively light, i.e., has arelatively small proportion of surface which accepts toner from themagnetic toner brush depletes the toner at a slower rate than one whichhas massive dark areas. In the toning of the latter type of image, thetoner is replenished more frequently than in the case of the former.

This mechanism for periodically replenishing the toner in the toner mixis an important feature of this apparatus in that it makes possible thecontinuous production of copies of substantially uniform density. Statedin another way, it avoids any progressive lightening of the copiesresulting from the progressive depletion of the toner from the tonermix.

The toner unit and its means for the rotation of the sleeves of itsmagnetic brush units, its agitators, and its toner feed cylinder form aself-contained unit which can be displaced laterally from its normaloperating position to bring it outside the cabinet of the apparatus inwhich it is used or completely removed therefrom to permit thereplenishment of the toner or the enriched toner mix. This is a valuablefeature of this apparatus in that it permits the convenientreplenishment of the toner outside the cabinet of the apparatus.

The fact that the toner unit is a selfcontained unit which is readilyremovable from the apparatus is an advantageous feature from twoadditional standpoints. In the event that the unit requires repair, aduplicate unit can be inserted in the apparatus and the operation of theapparatus continued without Waiting for the completion of the repairs onthe original unit. Again, when it is desired to change the toner beingused, either the color or the polarity thereof, the toner unit as wholecan be readily changed, thereby avoiding the necessity to clean a singleunit between changes of toner mix.

A means for vibrating the back of the photoelectrostatic sheet after ithas passed in contact with the magnetic toning brushes is located abovethe toner tray in a position forwardly of the magnetic brush unit or ofthe last magnetic brush unit, as the case may be, in the direction oftravel of the sheet. In a preferred embodiment of this apparatus, thevibrator is a cylindrical brush which is provided with a means for itsrotation around its horizontal axis which is at right angles to thedirection of travel of the sheet. This brush is in contact with the backof the sheet as it is carried forwardly by a conveyor system. Itspurpose is to cause any magnetic particles from the toner brush whichare mechanically adhering to the face of the sheet to drop back into thetoner tray. This vibratory action does not cause the particles of thetoner itself to drop off of the image areas of the sheet since they areheld in place by electrostatic force.

A shoe for each of the toner brush units of the toner unit is locatedabove the toner brush unit in a position to contact the back of thephotoelectrostatic sheet as its face surface is in contact with themagnetic brush formed by the brush unit. This shoe holds aphotoelectrostatic sheet carried by the conveyor system in uniformcontact with the magnetic brush as it passes over it. This shoe iselectrically insulated from the toner unit and is grounded through arelay switch. The toner unit itself is electrically insulated from theremainder of the apparatus and is electrically connected to a source ofdirect current which gives it a bias potential with respect to theelectrostatic image on the face of the photoelectrostatic sheet. Theelectrostatic image is negative in charge. The bias potential suppliedto the toner unit may be either positive or negative in charge as may bedesired. A positive charge on the toner unit increases the pickup oftoner by the surface of the photoelectrostatic sheet and intensifies thevisual image produced by the toning. However, it also tends to cause thebackground areas of the image to pick up toner causing the finished copyto have a dirty apperance. Despite the tendency of a negative biasvoltage to cause the background areas of the copy to have a dirtyappearance, the use of such a bias is sometimes desirable in thereproduction of original copy which has a light image which is diflicultto reproduce or which is desired in a copy of increased density.Generally, it is desirable to supply a negative bias potential to thetoner unit which is smaller in potential than the electrostatic chargeof the electrostatic image since such a bias has a relatively smalleffect on the density of the toned image, and which minimizes the pickupof toner particles by the background areas of the image. The net effectof a negative bias voltage is to cause the finished copy to be clean andcrisp in appearance. This net effect is desirable when reproducingoriginal copy which is even reasonably good.

I The shoes above the toner brush units are desirably longer than thewidth of the photoelectrostatic sheet which is toned. The combination ofshoes which are of'a length which extend at least to the edges of thesheet being toned and, preferably, somewhat beyond those edges with theuse of a magnetic toning brush which has a length equal to the width ofthe latent electrostatic image which is toned is advantageous in keepingthe side margins of the finished copy clean in appearance. The magneticbrush does not bring toner in contact with these marginal areas to bepicked up by any residual, negative electrostatic charge they may carryand the negative bias voltage tends to restrain the positive toner fromthose areas. The result is that the marginal areas can pick up little orno residual toner to give them a dirty appearance.

The bias voltage on the toner unit is applied only during the intervalduring which a photoelectrostatic sheet is passing over the toner unit.As noted hereinbefore, the electrical circuit which grounds the shoe orshoes of this toner unit carries a relay switch. This relay switch isaccurately timed in its operation by the electrical control system ofthe apparatus as will be fully described hereinafter to close as theleading edge of a sheet comes over the magnetic toning unit and to openthe instant that the trailing end of the sheet passes the unit. Whenthis relay switch is in open position, no bias potential is applied tothe unit. It is important that its closing and opening be accuratelysynchronzed with the passage of a sheet over the toning unit since theapplication of this bias voltage when a sheet is not between the shoe orshoes of the toning unit and the magnetic brush or brushes, as the casemay be, Will create a short circuit in the unit.

The toning apparatus in accordance with this invention has beengenerally described and some of its advantageous features pointed out inthe foregoing. A specific embodiment of this apparatus will now bedescribed with reference to the accompanying drawings in which likereference characters are used to refer to like parts wherever they mayoccur. In the drawings:

FIGURE 1 is an exploded, perspective view of the toner unit inaccordance with this invention showing the relationship between itscomponents;

FIGURE 2 is an elevational view of the end of the toner unit illustratedby FIGURE 1 showing the means for adjusting and locking its magneticcores in position;

FIGURE 3 i a cross-sectional view of the toner unit illustrated byFIGURE 1 and of the cooperating shoes associated therewith;

FIGURE 4 is a partially exploded perspective view of the conveyorsystem, of the vacuum platen in its offset position, of the toner unitand of the fuser unit of the apparatus described and claimed by ourcopending application, Ser. No. 189,758, filed Apr. 24, 1962, whichillustrates the relationship of the toner unit of this invention to therelated units in that particular apparatus;

FIGURE 5 is a fragmentary, perspective view of the receiving end of thefirst section of the conveyor system adjacent the vacuum platen of theapparatus described by our copending application, Ser. No. 189,758,filed Apr. 24, 1962, showing a gripper in open position and the detailsfor opening and closing the two grippers of the first section of theconveyor system in the position in which they receive a copy sheet fromthe vacuum platen of the apparatus;

FIGURE 6 is a fragmentary, perspective view of the delivery end of thefirst section of the conveyor system and of the receiving end of thesecond section thereof of the apparatus described by our copendingapplication, Ser. No. 189,758, filed Apr. 24, 1962, showing a gripper inopen position after delivering a copy sheet to the second section of theconveyor system; and

FIGURE 7 is an electrical wiring diagram showing the electrical circuitswhich control the toner unit illustrated by FIGURES 1, 2 and 3.

Referring specifically to FIGURES 1, 2 and 3, it will be seen that thistoner unit comprises a tray 10 which is divided into three compartments11, 12 and 13. The compartmcnt 11 carries the magnetic toner rolls 14and 15, the details of one of which are shown by FIGURE 1D, and fourtoner mixers E.6-16, the details of one of which are shown by FIGURE 1C.As best shown by FIGURE 3, the compartment 13 carries the toner feedroll 17, which forms a seal between that compartment and compartment 11when at rest. The details of this toner feed roll 17 are shown by FIGUREl-B. The compartment 12 carries the gear train, illustrated by FIGURE1E, which operates the two magnetic toner rolls 14, 15 and the fourtoner mixers 1616.

The magnetic toner rolls 14, 15 are identical in design and are rotatedin the same directions. Referring specifi cally to FIGURE 1D, it will beseen that the roll 14 or 15 comprises a stationary cylindrical core 18and a rotatable outer shell 19. The cylindrical core 18 is made of anon-magnetic material such as, for example, brass, and has a series ofsix longitudinal grooves 2tl2tl cut into its cylindrical surface atequally spaced intervals around approximately two-thirds of its totalcircumference. These longitudinal grooves carry permanent plastic magnetstrips 21-21. The cross-sections of these plastic magnets areillustrated by FIGURE 3 from which it will be seen that it is, ineffect, a longitudinal horseshoe magnet with its north pole 22 along oneof its upper margins, and its south pole 23 along the opposite uppermargin. As shown by FIGURE 1, the permanent magnet strips 2 -21 do notextend to the ends of the cylindrical core 18. The lengths of thesepermanent magnet strips are the width of the latent electrostatic imagewhich is to be toned by the magnetic brush unit.

The core 18 of this magnetic toner unit has coaxial shaft: ends 24 and25 as shown by FIGURE 1D. The shaft end 24 is cylindrical and is carriedby the bearing collar 26 in which it is free to rotate. The collar 26is, in turn, carried by the concentric collar 27, the outer surface ofwhich carries the keyways 28, 2 8. The collar 27 is fitted into the endof the outer cylinder 19 with a tight slip fit and is attached theretoby set screws not shown by the drawings. The inner surface of the collar27 is adjacent the end of the core 18 which carries the shaft end 24.

Referring specifically to FIGURE 1E, the member 29 has a cylindricalsection 30 carrying keys 31, 31 and a shaft section 32. This cylindricalsection 3% fits into the concentric opening of the collar 27 with thekeys 31, 31 in the keyways 28, 28. The cylindrical shaft section 3?. iscarried by the bearing collar 33 which is within the perforation 34 inthe wall of the compartment 11. The end of the shaft section 32 iswithin the gear compartment E2 of the toner unit and is connected to thegear train of the unit as will be fully described hereinafter.

The shaft end 25 has a short, cylindrical section directly adjacent theend of the core 18 which carries the bearing collar 35 which, in turn,carries the concentric collar 3a which is fitted into the end of theouter cylinder with a tight slip fit and attached thereto by set screws.

The shaft end 25 has an outer fiat sided section which is fitted intothe channel 37 of the shaft adjuster designated generally by the numeral3&5. The cylindrical section 39 of the member 49 of the shaft adjusterunit 38 is carried by the semi-circular perforation 41 in the wall ofcompartment 11 with its rim section in the compartment in a position tobear against the inner edge of the perforation 41.

The member 40 of the shaft adjuster un t 38 has a threaded, coaxialperforation which carries the thumb screw 43, which has a centered pointon a cortical, inner end which centers itself in a centered, conicaldepression in the end of the shaft section 25. This thumb screw alignsthe surface of the outer cylinder with the remainder of the toner unit.

The cylindrical surface of section 39 of the shaft adjuster member 49has a groove 41 near its outer end which is outside the wall ofcompartment 11. This groove receives the end of the set screw 45 whichcan be seen by reference to FIGURE 2. This set screw locks the shaftadjuster unit in any desired rotational position within the perforation41 of the wall of compartment 11. The adjustment of the rotationalposition of the shaft adjuster unit 38 determines the rotationalposition of the shaft end 25 and of the core cylinder 18 with respect tothe toner unit as a whole.

The adjustability of the rotational position of the core 18 and of theplastic magnets 21 21 which it carries is an important feature of thistoner unit in that it enables maximum eificiency to be obtained in theapplication of toner to a latent electrostatic image carried by aphotoelectrostatic sheet passed over the toner unit by a conveyor systemof the appaartus. The adjustment of the position of the core 1'8 toobtain maximum efficiency in the toning operation is made on the basisof trial and error. Although theories can be advanced on the basis thatthe positions of the north pole and the south pole edges of the plasticmagnets should be in specific positions relative to the tangential pathof travel of the photoelectrostatic sheet carrying the electrostaticimage being toned, the trial and error adjustment is the simplest andmost direct means for obtaining maximum efficiency in the toningoperation.

As best shown by FIGURE 3, each of the two magnetic toner rolls 14 and15 are, respectively, rovided with the doctor blades designatedgenerally by the numerals 46 and 47. The details of these doctor bladesare identical and are shown by FIGURE 1D for doctor blades 47. Referringspecifically to FIGURE 1D, it will be seen that the blade 47 is providedwith end brackets, one of which is the mirror image of the other. Theend bracket 49 is shown by FIGURE 1D. Each of these end brackets isprovided with two surfaces 50 and 51 which are at an angle ofapproximately forty-five degrees to each other. The section of thebracket forming surface 50 is provided with an oval perforation 52through which the screw 53 passes to adjustably attach the bracket 49 tothe top of the side wall of compartment 11 of the toner unit. The angledsurface 51 is tapped to receive the screw 54 by which the end of theblade 47 is adjustably attached to the surface 51 through the ovalperforation 55 near the end of the blade.

The screws 53, 53 and 54, 54 permit the edge of the blade 47 to beaccurately adjusted to parallel the cylindrical surface of the shell 19of the toner roll with a clearance which determines the height of themagnetic brush which comes into contact with the electrostatic image ona photoelectrostatic sheet. The edges of the doctor blades 46, 47 arebelow the horizontal tangent passing through the upper end of thevertical iameters of the magnetic toner units. The excess toner mixwhich is removed by the action of the doctor blades 46, 47 falls backinto the toner mix tray.

Referring specifically to FIGURE 3, it will be seen that the angulatedplate member 56 is located between the 9 magnetic toner rolls 14 and 15in a position such that its upper surface receives the toner mix fallingfrom the surface of the shell 19 of the roll 15 adjacent the part of itscore 18 which carries no magnets to retain the toner mix as a magneticbrush. This member 56 causes the toner mix dropped by the toner unit tofall into the toner mix in the bottom of the compartment 11 at alocation such that it cannot be immediately picked up by the roll 15without being admixed with the body of the toner mix in the bottom ofthat compartment.

The four mechanical stirrers 16a, 16b, 16c, 16d near the bottom of thecompartment 11 and below the magnetic toner rolls 14 and 15 agitate andmix the toner mix in the bottom of the compartment 11. The stirrers 16aand 160 are rotated by the gear train in clockwise direction, while thestirrers 16b and 16d, like the shells of the mag netic toner rolls 14,15, are rotated in the reverse directron.

The mechanical stirrers 1616 are identical in construction the detailsof one of which are illustrated by FIGURE l-C. The mechanical stirrer 16comprises a rod 57 which is generally hexagonal in cross-section withcylindrical end sections 58, 59. The alternate surfaces of the hexagonalsection of the rod 57 each carry four elongated loops Gil-60 which arespaced apart along each surface. The loops on the alternating surfacesaround the rod are in stepped positions with respect to the length ofthe rod.

The cylindrical end section 58 of the rod 57 passes through a bearing 61carried by the wall of compartment 11 and extends into the compartment12 carrying the gear train of the unit. The end of section 58 of thestirrer 16a is attached to the gear 62 of FIGURE 1E which is locatedwithin compartment 12. The corresponding ends of the stirrers 16b, 16cand 16d, respectively, carry the gears 63,64 and 65.

Referring again to FIGURE l-C, the end section 59 of the stirrer 16 iscarried by the bearing 66 which is located in a perforation in the wallof compartment 11 opposite that through which it carries the end section58.

FIGURE 1E illustrates the gear train by which the shells 19, 19 of themagnetic toner rolls 14 and 15 and the mechanical stirrers 16a, 16b, 16cand 16d are driven. The main drive sprocket 67 of this train is outsidethe wall of compartment 12, as shown by FIGURE 1A, while the remainderof that gear train is within that compartment. The shaft 68 isdetachably connected to the sprocket 67 by a self-centering, -multi-jawcoupling 69. One of the two elements of this coupling 69 is attached tothe sprocket 67, while the other is attached to the end of the shaft 68.This coupling 69 is located outside the wall of compartment 12. Theshaft 68 is carried by a bearing in the wall of compartment 12.

The coupling 69 is disconnected by a movement of the toner unit awayfrom the sprocket 67. This coupling permits the toner unit to be pulledpartially or wholly out of the cabinet of the apparatus in which thetoner unit is located through the door 70 for the replenishment of tonerin its compartment 13 for servicing or for the substitution of aduplicate unit. This is an advantageous feature of this apparatus bothfrom the standpoint of the convenience in the replenishment of the tonerand the ease with which the toner unit can be replaced with a duplicateunit.

Referring specifically to FIGURE 1-E, the shaft 68 carries the gears 71and 72 which are keyed together by the pin 73. The gear 72 meshes withthe gear 63 which, in turn, meshes on one side with the gear 62 and onthe other with gear 64. The gear 64, in turn, meshes with gear 65. Asshown by the arrows of FIGURE l-E, this meshing of the gears causesgears 62 and 64 to rotate in the opposite direction. As already noted,the gears 62, 63, 64 and 65 are, respectively, carried by the shaft endsof the stirrers 16a, 16b, 16c, and 16d respectively.

Still referring to FIGURE 1E, the gear 71 is the main drive for theshells 19, 19 of the magnetic toner rolls 14 and 15. The gear 71 mesheswith the gears 74 and 75 which are idler gears and, respectively, meshwith gears 76 and 77 which drive the shells of magnetic toner rolls 14and 15 through key members 29. Each of the gears 76 and 77 is attachedto the shaft sections 32, 32 of the key members 29, 29 which are, inturn, keyed to the shells 19, 19 of the magnetic toner rolls 14 and 15as described hereinbefore with reference to FIGURE 1-D. The top of thecompartment 12 carrying the gear train is closed by a cover 78 toprotect the gear train from foreign matter.

The brackets 48 and 49 of the doctor blades 46 and 47 also carry theends of the axles of the nylon rollers 79 and 80, shown by FIGURE 3,which extend longitudinally above the upper surfaces of the blades 46and 47. The position of these nylon rollers with respect to the doctorblades 46 and 47 is best shown by FIGURE 3. The rollers 79 and 80 areinsulating idlers which prevent the trailing end of a photoelectrostaticsheet being carried over the toner unit from dragging over the surfaceof the blades 46 and 47 and interrupting the downwardly flow of thetoner mix over their upper surface.

The toner mix feed roll 17 extends across the toner mix feed compartment13 adjacent the longitudinal slot 81 along the bottom of the compartment13 as can best be seen by reference to the cross-sectional view of thetoner unit shown by FIGURE 3. The toner mix feed roll 17 has a generallycylindrical surface which carries longitudinal grooves or serrations.When at rest, this toner mix feed roll substantially seals the slot 81,but due to its serrations, when rotated transfers an enriched toner mixor toner powder from the compartent 13 to the com partment 11 carryingthe magnetic toning rolls 14 and 15.

The roll 17 is provided with cylindrical shaft ends 82 and 83. The shaftend 82 is carried by the bearing 84 in the side wall of the compartment13 while the shaft end 83 is carried by the bearing 85 in the oppositeside wall of the compartment 13 and extends through the bearing 85 toposition a stub section outside that wall of compartment 13.

Referring specifically to FIGURE 2, it will be seen that the outer endof the shaft end 83 carries the rachet wheel 86 which is keyed theretoand the rachet arm 87 which is pivotally mounted thereon. The upperportion of the rachet arm 87 carries a spring loaded, pivotally mounted,rachet pawl 88 the edge of which bears on the rachet wheel 86. The pivot89 carrying the rachet pawl is lo cated on the rachet arm 87 withrespect to the end of the shaft end 83 which carries the-rachet arm in aposition such that when the lower end of the lever is moved laterally,shown as being to the left of FIGURE 2, the edge of the pawl engages therachet wheel causing it to rotate, a minor fraction of its totalcircumference. This rotation of the rachet wheel 86 by the action of therachet arm 87 causes a corresponding rotation of the toner mix feed rollwhich delivers an increasement of enriched toner mix or toner powdercontained in compartment 13 to a body of toner mix carried bycompartment 11 after each second such successive movement.

The rachet wheel 86 has a second pawl 90 having an edge bearing on itsteeth. This pawl is loaded with a spring 91 which holds its edge againstthe rachet wheel 86 and permits the edge to ride over the teeth as therachet wheel is rotated forwardly by the rachet arm 87 and the pawl 83but prevents the rachet wheel from rotating in the reverse directionwhen the pawl 83 is drawn backwardly.

The lower end of the rachet arm 87 carries a pin 92 which is attached tothe core 93 of the solenoid 94 by the hook 95. The hook 95 is attachedat one end to the end of the solenoid core 93 by a pivot and at theother end to the pin 92 by the channel 96 near its opposite end. Thischannel 96 can be removed from the pin 92 and the hook 95 is pivoted toget it out of the way when it is desired to remove the toner unit fromthe apparatus. The lower end of the rachet arm 87 is attached to thespring 97 which exerts tension which tends to pull the bottom of thelever in the direction to the right as illustrated by FIGURE 3 whichcauses the pawl 83 to move backwardly over the rachet wheel 86.

When the solenoid 94 is energized, it retracts its core 93 which pullsthe lower end of the rachet arm to the left as shown by FIGURE 3 in thedirection which causes the pawl 83 to move the rachet wheel 36 in aforwardly direction and, thereby, feed an increasement of enriched tonermix or toner powder from compartment 13 to com partment 11. The solenoid94 is energized by the electrical system of the apparatus as will befully described hereinafter.

The solenoid core 93 operates against the tension of the spring 97 as itis retracted. Upon reaching its fully retracted position, the solenoid94 is de-energized by the operation of the rod 98 connecting the outerend of the solenoid core and the switch 99 of the electrical systemdescribed hereinafter. When the solenoid is de-energized, the spring 97returns the solenoid core to its extended position, the bottom of therachet arm to its original position, and places the pawl 83 in positionagain to move the rachet wheel 86 forwardly to feed another increasemcntof enriched toner mixture or toner powder. As already noted, the pawl 90holds the rachet wheel 86 against the backwardly movement of the pawl88.

Referring again to FIGURE 3, it will be seen that the shoes 100 and 101are, respectively, positioned above the magnetic toner rolls 14 and 15.These shoes 100 and 101 serve two functions. First, the back of aphotoelectrostatic sheet being carried over the magnetic toner rolls 14and by a conveyor system passes in contact with the lower section ofthese shoes which hold the reverse surface in contact with the magneticbrushes of the toner rolls 14, 15 to permit a uniform toning of theelectrostatic image carried by that surface. Second, these shoes providea ground contact for the application of a bias voltage applied by theoperation of the electrical system of the apparatus.

FIGURE 4 illustrates the relationship of the toner unit in accordancewith this invention to related units of the automatic apparatus forphotoelectrostatic reproduction described and claimed in our copendingapplication Ser. No. 189,758 filed Apr. 24, 1962, now Patent No. 3,180,-239. This toner unit is well adapted for use as an esserr tial componentof the automatic apparatus described by that application. However, asalready noted, it is equally well adapted for use in any apparatus forphotoelectrostatic reproduction which develops a latent electrostaticimage by the use of a powdered solid resinous toner.

Referring specifically to FIGURE 4, the numeral 110 generally designatesthe toner unit described in detail hereinbefore with reference toFIGURES 1, 2 and 3. Adjacent to this toner unit 110 and on approximatelythe same horizontal level are the corona discharge unit 111, the vacuumplaten 112, the carrier plate 113 forming a part of the sheet feedingunit of the apparatus, and a stack of photoelectrostatic sheets 114 onthe carrier plate 113.

The first section 115 of the conveyor system of the apparatus consistingof two parallel belts or chains 116 and 117 which travel in parallelvertical planes and, respectively, pass adjacent the ends of the tonerunit 110 then upwardly and finally at a slight angle to a horizontalplane for a short distance. The chains 116 and 117 carry two sheetgrippers 118 and 119 which are, respectively, adapted to grasp a sheetcarried by the vacuum platen when it is in a laterally displacedposition as illustrated by FIGURE 4, carried over and in contact withthe magnetic brushes of the toner rolls 14 and 15 of the toner unit 110and under its bias shoes 100 and 101 with the latent electrostatic imagewhich it carries facing downw-ardly. This unit applies a powdered solidtoner to its latent electrostatic image on the surface of the sheet. Thesheet grippers 118 and 119 are apart on the belts or chains 116 and 117by one-half the equal lengths of the two belts or chains.

The second section 120 of the conveyor system comprises a plurality ofbelts and extends from the upper end of the first section along aslightly inclined plane to the third section 121 of the system. Thesecond section of the conveyor system is adapted to receive andtransport a sheet released by the sheet gripper 113 or 119 to the thirdsection of the conveyor system. The fuser unit 122 is located above thethird section 121 of the conveyor system. This third section 121 carriesthe photoelectrostatic sheet under the fuser unit 122 with its tonedimage facing upwardly to fuse the toner powder and make the imagepermanent. This third section of the conveyor then carries the sheetupwardly and delivers it to the delivery station 123 of the apparatus.

The drive for this first section of the conveyor system and for thetoner unit 110 is illustrated by FIGURE 4 as a broken away unitdesignated generally by the numeral 124. It will be noted that thebroken away unit duplicates the showing of the drive sprocket 125 whichfixes the position of this unit relative to the remainder of theconveyor system. It consists of an electric motor 126 provided with anelectrically activated brake 127 and a speed reducer 128 which drivessprocket 129. Sprocket 129 drives sprocket 130 through the chain 131.The sprocket 130 is on one end of the axle 132, the other end of whichcarries the sprocket 133 which drives sprocket 67 through theelectrically insulating timing belt 134 which carries teeth whichpositively engage the teeth of sprockets 133 and 67. The belt 134 may,for example, be made of rubber. It serves to insulate the toner unit 110from the remainder of the drive mechanism of the conveyor system. Thesprocket 67 is the main drive for te toner unit 110. The axle 132carries a third sprocket 6' .djacent sprocket 130, which drives sprocket125 through chain 137 which passes around the idler sprocket 138.

As shown by FIGURE 4, the sprocket 125 is atfixed to the end of the axle139 which carries the sprockets 140, 140 which drive the conveyortransport chains 116, 117 of the first section of this conveyor system.The axle 139 carries a fourth sprocket 141 which drives sprocket 142through chain 143. The sprocket 142 is affixed to the end of an axlewhich carries a vibrator 144. The vibrator 144 may, for example, be abrush with bristles which extend through the slots in the adjacent sweep145. The rotation of this brush vibrator 144 vibrates the back of a copysheet passing around the opposite side of the sweep 145 and causes anymechanically adhering particles of iron from the toner mix to drop fromthe surface of the sheet.

The revolving brush vibrator described in the foregoing is only one ofseveral forms of vibrators which are suitable for use in this apparatus.An alternative form, which may be positioned above the upper edge of thesweep 145 is a rotating bar having an irregular surface which contactsthe back of a sheet of copy paper just after it has 60 passed around thesweep and causes the sheet to vibrate.

Referring specifically to FIGURE 4, it will be noted that a series ofsix limit switches 146, 147, 148, 149, and 151 are spaced at accuratelypredetermined intervals along the path of the downward or return travelof the 65 transport chain 116. That chain carries two lugs, not shown bythe drawings, which are, respectively, precisely spaced on the chain inrelation to the position of the grippers 118 and 119 one end of each ofwhich is carried by the chain. The tripping arms of each of the limitswitches 146,

70 147, 148, 149, 156 and 151 are in a position relative to the path oftravel of the adjacent chain 116 such that the lugs carried by the chainwill trip the switch as they pass.

The contact between one of the lugs carried by the chain 116 and thetripping arm of the limit switch 146 cocks a relay which controls thebrake 127 on the shaft of the electric motor 126 and the operation ofthat motor in driving the transport chains 116 and 117 as well as thesprocket 67 which is the main drive for the toner unit 110. Thefollowing contact between that lug and the tripping arm of the limitswitch 147 activates the control relay which stops the motor 126 byapplying the brake 127 to instantaneously stop the rotation of itsshaft. The lug on the chain 116 and the tripping arm of the limit switch147 are in exact positions to stop the motor 126 and the movement of thechains 116, 117 at the precise position which places the gripper 118 or119 as the case may be in the position illustrated in the case ofgripper 118 by FIGURE 4. The position of gripper 119 when gripper 118 isin the position also shown by FIGURE 4.

The limit switches 148, 149, 150 and 151 control the application of abias potential to the shoes 1% and 101 of the toner unit 110 as will bedescribed hereinafter with reference to FIGURE 5.

Still referring to FIGURE 4, as noted above, the belts or chains 116 and117 are driven by the sprockets 140, 140, pass upwardly to pass aroundsprockets 152, 152; 153, 153; and 154, 154; then downwardly to passaround 155, 155; 156, 156; 157, 157; and to finally return around thedrive sprockets 140, 140.

FIGURE shows the end of the first section of the conveyor adjacent thevacuum platen 112 with the gripper 118 in open positions ready toreceive the edge of a copy sheet 166 by the lateral displacement of theplaten 112. It will be noted that FIGURE 4 shows this gripper closedover the end of the copy sheet 166. The sprockets 157, 157 and 156, 156one of each pair of which is shown by FIGURE 5 fixes the relationship ofthis broken figure to that illustrated by FIGURE 4.

Referring specifically to FIGURE 5, the numeral 170 designates an axle,the ends of which are carried by the frame members 171 and 172 which areaffixed to the main frame of the apparatus. One end of the axle 170extends beyond the outer side of the frame member 172 and carries thelever arm1'73. The lever 173 is held in a vertical position by having anend section in a notch in the lower edge of the lever arm 174. One endof the lever arm 174 is pivoted on a pin 175 attached to the framemember 172 and the other end is attached to the end of the core 176 ofthe solenoid 177 by a pivot joint.

The axle 170 carries two arms 173, 178 which have rollers 179, 179positioned to bear on the arcuate lever arms 1 80, 180 of the gripper118 and to force them upwardly when the lever 173 is held in position bythe lever arm 174. The lever arms 180, 180 of the gripper are attachedto the upper leaf thereof, and when forced upwardly, cause the gripperto open as illustrated by FIGURE 5. As shown by FIGURE 5, the arms 178,178 are in an inclined position when they are held in position to openthe gripper 118.

The activation 'of the solenoid 177 causes it to raise the .end of thelever arm 174 freeing the axle 176 to rotate a fraction of a turn in thecounterclockwise direction. This rotation of the axle 170 is caused bythe weight of the arms 178, 178 and the rollers 179, 179 causing thearms to fall from their inclined position. The rotation of the axle 170is stopped by the lever arm 178 coming to rest against the pin 181. Thisrotation removes the rollers 179, 179 from their contact with the levers180, 180 and permits the gripper 118 to close under tension provided bya spring in its hinge. The solenoid 177 is activated by the electricalcontrol system to cause the gripper 118 to close at the instant that thevacuum platen 112 reaches its laterally displaced position placing theedge of a copy sheet in position to be grasped by the gripper.

The pin181 is in a location such that when the lever arm 173 is restingagainst it, the 0am rollers 179, 179 are in the path of travel of thegripper lever arms 180, 180. As the gripper 118 moves into the positionshown 1 1 by FIGURE 5, the lever arms 180, 180 bring the arms 178, 178and the axle to the position shown by FEGURE 5 and causes the lever arm173 to become locked in its vertical position by the lever arm 174. Inthis position, the leaves of gripper 118 are held in their open positionas shown by FIGURE 5.

It is essential that gripper 118 come to an accurately positioned stopin the position in which it is illustrated in FIGURE 5. This positionmust be accurate to permit the gripper to receive the edge of a copysheet from the vacuum platen 112 as it comes to its laterally displacedposition just prior to the end of the cycle of operations of the vacuumplaten transport system. Similarly, the gripper 119 must be stopped atexactly the same location when it is, in turn, carried around by theconveyor chains to receive a copy sheet.

FIGURE 6 shows the detail of the upper or forward end of the firstsection of the conveyor system together with the backward end of thesecond section of that system and shows the gripper 119 at the instantafter it has been forced into its open position to deliver a copy sheetthat it is carrying to the second section 120 of the conveyor system.The gripper 118 and 119, as the case may be, is not stopped in beingopened to deliver a copy sheet to the second section of the transportsystem, but is opened and then permitted to close under its own springloading while the transport chains are in motion. The movement of thetransport chains is stopped only when one of these grippers comes intoposition to receive a copy sheet as described hereinbefore.

Referring specificaily to FIGURE 6, it will be seen that the copy sheet182 is being carried by the belts of the second section of the transportsystem and is held on those belts by the spring loaded rollers 183, 133.The leading edge of the copy sheet has just been released by the openingof the gripper 119 in its forward travel. The gripper 119 has pulledaway from the leading edge of the copy sheet 182 because the firstsection of the conveyor system travels at a somewhat faster rate thanits second section.

The gripper 119 has been forced open by the arcuate lever arms 180,riding under the surfaces of the anvil blocks forming the upper sectionof the element 184 which force the ends of the lever arms downwardly.The chains 116, 117 of the first section 115 of the conveyor system areriding over the shoes on the upper surface of the lower section of theelement 184 which are beneath the chains at the location that the chainsare placed under stress by the contact between the lever arms 181i, 180and the anvil blocks 184, 184. The shoes 185, 185 prevent this stressfrom causing the chain to sag, and thereby interfere with the opening ofthe gripper 119.

Still referring to FIGURE 6, as the gripper 119 is moved forwardly, itsarcuate lever arms 180, '180 ride out from under the anvil blocks184,184. Upon being released from their depressed position, the arms 180139 cease to counteract the spring tension which closes the gripper 119and the gripper closes. The movement of the chains 116, 117 continuesuntil they reach the approximate position shown in broken outlinedesignated 119A at which point its return movement is stopped while thegripper 118 receives a copy sheet as described with reference to FIGURE5 Our copending application Ser. No. 189,758 filed Apr. 24, 1962describes in detail an automatic electrical control circuit of anapparatus for the automatic photoelectrostatic reproduction of images ofwhich the toner unit of this invention is adapted to form an essentialpart. That automatic electrical control circuit comprises a series ofstepping switches and relays together with related elements. It does notform a part of this invention and will not be described in thisspecification. However, the relationship of the various electricalcomponents of the apparatus of this invention to the automatic controlcircuit, insofar as it relates to the control of the toner unit 119,with respect to the first section 115, the second section 120 and thethird section 123 of the conveyor system associated with the toner unit110 will be described with reference to FIGURE 7. The relationship ofthe automatic control circuit to the toner replenishment system of thetoner unit 110 will be described with reference to FIGURE 7.

Referring specfically to FIGURE 7, it will be seen that the automaticelectrical control circuit is indicated generally by the numeral 1%.This automatic electrical control circuit is connected by the electricalline 191 through the fuse 192 and the electrical line 191 through thefuse 192 and the electrical line 193 to the double pole starting switch194 of the apparatus which is, in turn, connected by the line 195 to oneside 0!? a suitable source of alternating electric current which may be,for example, a 110 volt, 60 cycle current. The second terminal of thestarting switch 19-4 is connected by the line 196 to the other side ofthe source of alternating current and the corresponding terminal of theswitch 194 is con nected to the line 197.

The line 197 is connected to one terminal of each of the winding of thesolenoid 177; the electric motor 1.26; the limit switches 146, 147, 148,149, 150 and 151; the electric motor 169 and the electric motor 17%. Thesecond terminals of each of the winding of the solenoid 177; theelectric motor 126; the limit switches 146, 147, 148, 149, 150 and 151are connected, respectively, by the electrical lines 198, 199, 260,2111, 202, 293, 204 and 205 to the automatic control circuit 191). Thesecond terminals of the electric motor 169 and the electric motor 170are each connected to the electrical line 191.

The terminals of the electric brake 127 on the motor are, respectively,connected by the electrical lines 208 and 2tl9 to the automatic controlcircuit 199. The electrical control circuit 190 is also connected to theelectrical line 197.

Referring both to FIGURE 7 and to FTGURE 4, the closing of the startingswitch 194 activates the automatic control circuit 190 and places theelectric motors 169 and 170 in operation. These motors operatecontinuously as long as the switch 194 is closed, i.e., as long as theapparatus as a whole is in operation. Referring again to FIGURE 4, itwill be seen that the operation of the motor 169 drives the belts of thesecond section 12%) of this conveyor system as well as the single widebelt of the third section 121 of the apparatus. The operation of themotor 170 drives the roll of the third section 121 of the system.

The electrical components of this conveyor system other than itselectric motors 169 and 171) are under the direct control of theautomatic control circuit 196 and are timed in their operation by thecontrol circuit with respect to other operations of thephoto-electrostatic copy apparatus of which this conveyor system isadapted to form an essential component. The cycle of operation of thisconveyor system is initiated by the automatic control circuit 190 whenthe vacuum platen 112 of the copy apparatus completes a cycle of itsoperations to the point at which it returns to its displaced positionadjacent the position in which it receives a copy sheet to begin itscycle of operations.

When the vacuum platen 112 reaches its displaced position, one of thesheet grippers 118 or 119 is in its open position adjacent the vacuumplaten as illustrated by gripper 113 shown by FIGURE 6. The vacuumplaten 112 by its lateral movement places an edge of the copy sheetwhich it is carrying between the leaves of the gripper in a position tobe grasped by the gripper when its leaves are closed by the springtension on its hinge.

The automatic control circuit 196 causes the gripper 118 or 119, as thecase may be, to grasp the or o of a copy sheet 166 as soon as the vacuumplaten 112 reaches Cir 16 its laterally displaced position byde-energizing the winding of the solenoid 177 which was energized at theend of a prior cycle of operation of the first section of this conveyorsystem as will be explained hereinafter. The tie-energizing of thewinding of the solenoid 177 permits the rollers 179, 179 to drop awayfrom the arcuate arms 130, 180, in turn, permitting the gripper 113 or119 to close under the spring tension of its hinge.

After the Winding of the solenoid 177 is de-energized and the gripper118 or 119 has gripped the edge of a copy sheet 166, the automaticcontrol circuit 190 shuts off the DC. voltage on the brake 127 of theelectric motor 126 which had been applied at the end of the precedingcycle of operation of this conveyor system. At the same time, theautomatic control system energizes the motor 127 to start the transportchains or belts 116 and 117 of the first section 115 of this conveyor inmotion to carry the copy sheet over the toner unit 110 and under thetoner bias shoes 1% and 101 and on to the second section of thisconveyor system.

he energizing of the motor 126 to place the first section of theconveyor system in motion also places the outer shells 19, 19 of thetoner rolls 14 and 15 in motion by the action of the sprocket 67. Therotation of these shells forms a magnetic brush on their surfaces whichcarry particles of a resinous toner powder. As the copy sheet 166 iscarried forwardly by the gripper 118, its lower surface comes intocontact with the magnetic brushes carried by the toner rolls 1.4 and 15and the particles of the resinous toner adhere selectively to a latentelectrostatic image carried by its surface. At the same time, the tonerstirrers 1616 are rotated by the gear train of the toner unit 118 tokeep the toner mixture supplied to toner rolls 14 and 15 supplied withtoner powder which is selectively removed from the magnetic brushcarried by the rolls.

The automatic control closes the current supply to the bias shoes 1% and191 and readies them to supply a bias voltage to these shoes at any timethe shoe 100 or 101, or both, are grounded by the operation of theirassociated limit switches. The movement of this first section 115 ofthis conveyor system causes the normally open limit switches 143 toclose by contact with one of the two lugs on the transport chain 116,completing the circuit of the bias shoe 1% to ground. This bias shoe 100remains grounded with its bias current operable until the same lug onthe transport chain 116 contacts the normally closed limit switch 15%,opening it, thereby causing the automatic control circuit 190 to openthe circuit between the bias shoe 109 and ground.

The tripping arm of the switch 148 and the two lugs on the transportchain 116 are precisely positioned with respect to each other and withrespect to the location of the grippers and 119 on the transport chains116 and 117 to cause the bias shoe 100 to become grounded at the momentthe leading edge of the electrostatic image is brought under the biasshoe. The tripping arm of switch 151: and the two lugs on the transportchain are precisely positioned with respect to the location of thegrippers on the transport chains 116 and 117 to cause the bias shoe 1%to be disconnected from ground at the moment the trailing edge of thecopy sheet passes under the bias shoe.

The ground connection of the bias shoe 1131 is established by theContact of a lug on the transport chain 116 with the tripping arm of theswitch 149 in exactly the same manner described above in connection withthe bias shoe 191) and the switch 148. Further, the ground connection ofthe bias shoe 101 is broken by the action of the switch 151 in exactlythe same manner as described above in connection with the bias shoe 1%and the switch 150.

The positions of the switches 14-9 and 151, the positions of the on thechain 115 and the positions of the grippers 138 and 119 on the chain 115relative to the bias shoe 191 are exactly the same as those of theswitches 17 1'48 and 152) relative to the position of the bias shoe 100,the lugs on the chain 116 and those of the grippers 118 and 119 on thechains 116 and 117 which have been described in the foregoing.

As can be seen by reference to FIGURE 4, the bias shoes 100 and 101 arespaced apart along the line of travel of the grippers 118 and 119. Theswitches 148 and 149 and the switches 150 and 151 are, respectively,spaced apart along the line of travel of the chain 116 by the samedistance as the bias shoes are spaced apart. The spacing betweenswitches 148 and 150 and between switches 149 and 151, respectively, areidentical. This spacing is the same as the length of the latentelectrostatic image which is toned by the toner unit 110 in thedirection of its forward travel along the conveyor system of theapparatus.

The opening of the limit switch 151 by contact with one of the two lugscarried by the chain 116 causes the automatic control circuit 190 torevert to its initial position in readiness to begin a new cycle ofoperations.

To apply a bias voltage through the bias shoes 100 and 101 when a lug onthe chain 116 contacts the tripping arm of the switch 146, the automaticcontrol circuit activates the brake 127 to stop the motor 126 toprecisely position a gripper 118 or 119 in position to receive the edgeof a copy sheet as illustrated by FIGURE 4.

Referring again to FIGURE 7, it will be seen that one terminal of thewinding of the solenoid 94 is connected to the electrical line 197 whileits second terminal of its winding is connected by the electrical line206 to the switch 99 which is, in turn, connected by the electrical line207 to the automatic control circuit 190 of the apparatus. The secondterminal of the solenoid 94 is connected by electrical line 229 toswitch 230 which has its second terminal connected to line 191.

The automatic control circuit is equipped with a series of sevenswitches 208, 209, 210, 211, 212, 213 and 214 which are, respectively,connected thereto by the electrical lines 215, 216; 217, 218; 219, 220;221, 222; 223, 224; 225, 226; and 227, 228. The momentary closing of theswitch 208 while the switches 209, 210, 211, 212, 213 and 214 are opendiscontinues the operation of that portion of the automatic controlcircuit which automatically operates the solenoid 94, permitting itsmanual operation by the switch 230. The momentary closing of the switch230 by the operator of the apparatus energizes the solenoid 94 andcauses it to add one increment of toner to the compartment 11 of thetoner unit 110.

The automatic control circuit 190 of the apparatus is equipped to supplyelectrical current through the line 99 and the normally closed switch 99to energize the solenoid 94 to cause it to retract its core and by meansof the rachet arm cause the movement to the toner feed roll 17 through afraction of its circumference to move an increment of toner fromcompartment 13 to compartment 11 of the toner unit 110 when the switches208 and 230 are open and one of the switches 209, 210, 211, 21-2 or 213is closed. The switch 99 opens when the solenoid core reaches its fullyretracted position and the core is returned to its extended position bythe tension of the spring 97. This action places the solenoid 94 incondition to supply another increment of toner powder to the compartment11 upon receiving another electrical pulse from the automatic controlcircuit 190.

In operating the solenoid in this manner, the automatic control circuit190 is adapted to supply an increment of toner powder in synchronismwith the operation of the first section 115 of the conveyor system ofthe apparatus at intervals determined by the particular one of theswitches 209, 210, 211, 212, 213 which is closed by the operator of theapparatus. For example, it may supply an electrical pulse and anincrement of toner after the toning of four, eight, twelve, sixteen ortwenty latent electrostatic images, as may be desired, by the operatorof the apparatus.

In tlie foregoing, many details of the to'hei apparatus in accordancewith this' invention have been given. It will bereadily apparent tothose skilled in theart that many variations can bemade in-the detailsof the ap= paratus without departing from the spirit ofthe'invention orthe scope of the clainis which followi- We claim:

1. A toner unit adapted for the application of a powdered, solidresinous toner to an electrostatic image carried by a photoelectrostaticcoating on a copy sheet which comprises in combination:

a stationary cylindrical core of a non-magnetic material having its axisin approximately a horizontal position, and a plurality of longitudinalgrooves countersunk in its cylindrical surface at spaced intervalsaround at least a substantial part of its circumference;

an elongated, closely fitting strip of a permanently magnetic materialpositioned within each of the said grooves in the surface of thestationary core;

a means for adjusting the circumferential position of the saidcylindrical core and for locking it in its adjusted position, wherebythe positions of the said magnetic strips with respect to the upperhorizontal tangent of the circumference of the said core can beaccurately adjusted;

a rotatable, hollow cylindrical core of a non-magnetic materialpositioned around the stationary core and the longitudinal magneticstrips carried in its cylindrical surface;

a tray for retaining a body of a toner mix in contact with the lowerpart of the said rotatable cylinder;

a means for rotating the said hollow cylinder around the said stationarycore; and

a doctor blade adjacent the said rotatable, hollow cylinder, parallelingthe length of the said cylinder, spaced away from its surface by auniform distance along its length, and adjacent a location at which thesurface of the cylinder is moved in an upwardly directionby the saidmeans for rotating it around the stationary core.

2. A toner unit adapted for the application of a powdered, solidresinous toner to an electrostatic image carried by a photoelectrostaticcoating on a copy sheet, which comprises in combination:

a stationary cylindrical core of a non-magnetic material having its axisin approximately a horizontal position, and a plurality of longitudinalgrooves countersunk in its cylindrical surface at spaced intervalsaround at least a substantial part of its circumference;

an elongated closely fitting strip of a permanently magnetic materialpositioned within each of the said grooves in the stationary core;

a rotatable hollow cylindrical core of a non-magnetic materialpositioned around the stationary core and the longitudinal magneticstrips carried in its cylindrical surface;

a tray comprising two elongated, side-by-side compartments which areconnected by a longitudinal slot near the bottom of the tray, one of thesaid compartments being adapted for retaining a body of toner mix incontact with the lower part of the said rotatable cylinder, and thesecond compartment being adapted for carrying a supply of an enrichedtoner mix;

at least one rotatable stirrer positioned at a level below the rotatablecylinder in the first compartment;

a means for rotating the said hollow cylinder around its stationarycore, and for rotating the said stirrer;

a grooved rotatable cylinder positioned within the second compartment ofthe said tray adjacent the longitudinal slot connecting that compartmentwith the first compartment, which closes the said slot when in astationary position, and when rotated, will transfer an enriched tonermixture from the second compartment into the first compartment; and

a means for causing the rotation of the said grooved cylinder in thesecond compartment through successive fractions of its circumference.

der outside the said second compartment;

a lever arm pivotally mounted adjacent the said rachet on the end of theaxle of the said grooved cylinder; pawl pivotally mounted on the saidlever arm adjacent the periphery of the said rachet in a position toengage and rotate the rachet through a fraction of its circumferencewhen the free end of the lever arm moves in one direction, but not whenit moves in the reverse direction;

second pawl which prevents any inadvertent movement of the said rachetwhen the lever arm is moved in the reverse direction;

solenoid, the core of which is pivotally connected to the free end ofthe said lever arm, the solenoid being in a position with respect to thelever arm to cause the movement of the end of the lever arm in thedirection which rotates the said rachet by the retraction of its coreupon being energized;

spring connected to the free end of the lever arm which exerts tensionon the lever arm to cause it to move in a direction reverse to that inwhich it is moved by the reaction of the solenoid core; and

an electrical means to provide electrical pulses to briefly energize thesaid solenoid.

The toner unit adapted for the application of a powdered, solid resinoustoner to an electrostatic image carried by a photoelectrostatic coatingon a copy sheet, described by claim 2, in which the means for causingthe rotation of the said grooved cylinder in the second compartmentthrough successive fractions of its circumference comprises incombination:

an electrical solenoid;

a mechanical means connected to the core of the said solenoid for therotation of the said grooved roll through a minor fraction of itscircumference each time the solenoid is energized;

an electrical means for setting any one of a plurality of electrostaticimages to be toned between consecutive electrical pulses to energize thesaid solenoid; and second electrical means controlled by the setting ofthe first electrical means which sends successive electrical pulses tothe said solenoid at intervals controlled by the setting of the firstelectrical means as to the number of electrostatic images to be tonedbetween consecutive pulses.

5. A toner mechanism for the application of a powdered, solid resinoustoner to an electrostatic image carried by a photoelectrostatic coatingon a copy sheet in the form of a self-contained unit which is adapted toform a readily removable, interchangeable component part of apparatusfor the photoelectrostatic reproduction of images, which comprises incombination:

tray which is subdivided into at least two compartments which aregenerally rectangular in shape, one of which is elongated and the secondof which is adjacent a shorter side of the elongated compartment;

two toner rolls positioned side-by-side in the elongated compartment,each of which comprises;

a stationary cylindrical core of a non-magnetic material having its axisin approximately a horizontal position, and a plurality of longitudinalgrooves countersunk in its cylindrical surface at equally spacedintervals around approximately two-thirds of its circumferenee;

an elongated, closely fitting, permanently magnetic plastic strippositioned within each of the said grooves of the stationary core;

a rotatable hollow cylindrical core of a non-magnetic materialpositioned around the stationary core, having the end of a shaftextending into the second compartment of the said tray;

four rotatable stirrers positioned near the first compartment at a levelbelow that of the said toner rolls, each of which having the end of itsshaft extending into the second compartment;

a means for adjusting the circumferential position of the saidcylindrical core, and for locking it into its adjusted position wtihrespect to one wall of the said tray; and

a gear train within the second compartment connected to the ends of theshafts of the said rotatable cylinders and the said stirrers, and to ashaft which extends through an outer wall of the said tray and carrieson its outer end one-half of a coupling which is adapted to mate with asecond half of the coupling which is connected to a source of rotarypower;

the said gear train being capable of rotating the said cylinders and thesaid stirrers when the said halfcoupling is rotated.

6. A toner mechanism for the application of a povdered, solid resinoustoner to an electrostatic image carried by a photoelectrostatic coatingon a copy sheet in the form of a self-contained unit which is adapted toform a redaily removable, interchangeable component part of apparatusfor the photoelectrostatic reproduction of images, which comprises incombination:

a tray which is subdivided into at least two compartments which aregenerally rectangular in shape, one of which is elongated and the secondof which is adjacent a shorter side of the elongated compartment;

two toner rolls positioned side-by-side in the elongated compartment,each of which comprises;

a stationary, cylindrical core of a non-magnetic material having itsaxis in approximately a horizontal position, and a plurality oflongitudinal grooves countersunk in its cylindrical surface at equallyspaced intervals around approximately two-thirds of its circumference;

an elongated, closely fitting, permanently magnetic plastic strippositioned within each of the said grooves of the stationary core;

a rotatable, hollow cylindrical core of a non-magnetic materialpositioned around the stationary core, having the end of a shaftextending into the second compartment of the said tray;

four rotatable stirrers positioned near the first compartment at a levelbelow that of the said toner rolls, each of which having the end of itsshaft extending into the second compartment;

a means for adjusting the circumferential position of the saidcylindrical core, and for locking it in its adjusted position withrespect to one wall of the said tray;

a doctor blade adjacent each of the said rotatable cylinders,paralleling the length of the said cylinder, spaced away from itssurface by a uniform distance along its length, and adjacent a locationat which the surface of the cylinder is moved in an upwardly direction;and

a gear train within the second compartment connected to the ends of theshafts of the said rotatable cylinders and the said stirrers, and to ashaft which extends through an outer wall of the said tray and carrieson its outer end one-half of a coupling which is adapted to mate with asecond half of the coupling which is connected to a source of rotarypower;

the said gear't'rain being capable of rot'ating the said cylinders andthe said stirrers when the said halfcoupling is rotated.

7. A toner mechanism for the application of a powdered, solid resinoustoner to an electrostatic image carried by a photoelectrostatic coatingon a copy sheet in the form of a self-contained unit which is adapted toform a readily removable, interchangeable component part of apparatusfor the photoelectrostatic reproduction of images, which comprises incombination:

a tray which is subdivided into three compartments which are generallyrectangular in shape, two of which are elongated, positionedside-by-side, and connected by a slot near the bottom of the tray, andthe third of which is adjacent one of the ends of the elongatedcompartments;

two toner rolls positioned side-by-side in one of the elongatedcompartments, each of which comprises;

a stationary cylindrical core of a non-magnetic material having its axisin approximately a horizontal position, and a plurality of longitudinalgrooves countersunk in its cylindrical surface at equally spacedintervals around approximately two-thirds of its circum ference;

an elongated, closely fitting, permanently magnetic plastic strippositioned within each of the said grooves of the stationary core;

a rotatable, hollow cylindrical core of a non-magnetic materialpositioned around the stationary core, having the end of a shaftextending into the third compartment of the said tray;

four rotatable stirrers positioned near the first compartment at a levelbelow that of the said toner rolls, each of which having the end of itsshaft extending into the third compartment;

a means for adjusting the circumferential position of the saidcylindrical core, and for locking it in its adjusted position withrespect to one wall of the said tray;

a gear train within the third compartment connected to the ends of theshafts of the said rotatable cylinders and the said stirrers, and to ashaft which extends through an outer wall of the said tray and carrieson its outer end one-half of a coupling which is adapted to mate with asecond half of the coupling which is connected to a source of rotarypower;

the said gear train being capable of rotating the said cylinders and thesaid stirrers when the said halfcoupling is rotated;

a grooved rotatable cylinder positioned Within the third compartment ofthe said tray adjacent the longitudinal slot connecting that compartmentwith the first compartment which closes the said slot when in astationary position, and when rotated, will transfer an enriched tonermixture from the third compartment into the first compartment; and

a means for causing the rotation of the said grooved cylinder in thethird compartment through successive fractions of its circumference,

8. An apparatus adapted for the reproduction of images onphotoelectrostatic copy sheets, which comprises in combination:

a conveyor adapted to carry a flexible sheet from one location toanother which includes:

a pair of continuous conveyor chains which are of the same length andspaced apart in vertical parallel planes;

a plurality of pairs of sprockets which engage the said chains and keepthem taut, two pairs of which are spaced apart to carry the said chainsin a substantially horizontal plane during a portion of their lengths;

a means for driving one pair of the sprockets carrying the said chain;and

at least one sheet gripper adapted to grasp the edge of a copy sheet,and to carry the sheet which is attached at its ends to the said chainswith its length normal to the said vertical planes;

a toner unit which includes:

a tray for holding a toner mixture, which is electrically insulated fromthe remainder of the apparatus;

a rotatable, magnetic toner roll within the said tray;

and

a means for rotating the said toner roll through an electric'allynon-conductive drive; and

a source of DC. electrical potential connected to the said unit;

the said unit being located below the parallel plane through which thesaid conveyor chains pass;

a bias shoe located above the said toner roll in a position to contactthe back of a copy sheet carried by the said gripper at the location atwhich its face is in contact with a magnetic brush of toner mixturecarried by the saidtoner roll, the said bias shoe being electricallyinsulated from the remainder of the ap paratus; and

an electrical means which is operated by the movement of one of the saidconveyor chains connected to the said shoe, which connects the shoe toground as the leading edge of a copy sheet is brought beneath it, andbreaks that connection when the trailing edge of the sheet reaches theshoe.

9. In apparatus adapted for the reproduction of images onphotoelectrostatic copy sheets, which comprises the combination of aconveyor adapted to carry a flexible sheet from one location to another,a toner unit, and a bias shoe described by claim 8, in which:

a first limit switch is positioned adjacent the path of travel of one ofthe conveyor chains;

a second limit switch is positioned adjacent the path of travel of thesame conveyor chain, and spaced forwardly along the line of travel ofthe chain from the location of the first limit switch;

a lug carried by the said conveyor chain which is adapted to trip thefirst limit switch and then the second limit switch as it is carriedpast them by the movement of the chain;

the said lug and the said limit switches being located with respect tothe length of the said conveyor chain and the location of the gripper onthe chain at positions such that when the gripper reaches a positionwhich brings the leading edge of the image area of a copy sheet beneaththe bias shoe, the first limit switch is tripped by the lug, and whenthe gripper reaches a position which brings the trailing edge of theimage area of the copy sheet beneath the bias shoe, the second limitswitch is tripped; and

an electrical system connected between the limit switches and the biasshoe which establishes an electrical connection between the bias shoeand ground when the first limit switch is tripped, and then breaks thesaid electrical connection when the second limit switch is tripped.

10. -In apparatus adapted for the reproduction of images onphotoelectrostatic copy sheets, which comprises in combination:

a conveyor adapted to carry a flexible sheet from one location toanother which includes:

a pair of continuous conveyor chins which are of the same length andspaced apart in vertical parallel planes;

a plurality of pairs of sprockets which engage the said chains and keepthem taut, two pairs of which are spaced apart to carry the said chainsin a substantially horizontal plane during a portion of their lengths;

a means for driving one pair of the sprockets carrying the said chain;and

two sheet grippers, each of which is adapted to grasp the edge of a copysheet and to carry the sheet which is attached at its ends to the saidchains with its length normal to the said vertical planes, the saidsheet grippers being spaced apart along the length of the chains byapproximately one-half their lengths;

a toner unit which includes:

a tray for holding a toner mixture which is electrically insulated fromthe remainder of the apparatus;

two rotatable, magnetic toner rolls positioned side-by side within thesaid tray;

a means for rotating the said toner rolls through an electricallynon-conductive drive; and

a source of DC. electrical potential connected to the said unit;

the said unit being located below the parallel plane through which thesaid conveyor chains pass;

a bias shoe located above each of the said toner rolls in a position tocontact the back of a copy sheet carried by one of the said grippers atthe location at which its face is in contact with a magnetic brush of atoner mixture carried by the adjacent toner roll, each of the said biasshoes being electrically insulated from each other and from theremainder of the apparatus; and

electrical means operated by the movement of one of the said conveyorchains connected to each of the said shoes, which connects the shoe toground as the leading edge of a copy sheet is brought beneatth it, andbreaks that connection when the trailing edge of the sheet reaches theshoe.

11. In apparatus adapted for the reproduction of images onphotoelectrostatic copy sheets, which comprises the combination of aconveyor adapted to carry a flexible sheet from one location to another,a toner unit including two toner rolls, and two bias shoes as describedby claim 9 in which:

a series of four limit switches are positioned adjacent the path oftravel of one of the conveyor chains, and spaced apart in the directionof its travel;

two lugs carried by the said conveyor chains which are adapted tosuccessively trip each of the four limit switches as they are carriedpast them by the movement of the chains;

the said lugs being spaced apart along the length of the chains byapproximately one-half of their lengths;

the said lugs and the said limit switches being located with respect tothe length of the conveyor chains and the location of the grippers onthe chain at positions such that when one of the grippers reaches aposition which brings the leading edge of the image area 2a of a copysheet beneath the first of the two bias shoes in the direction of travelof the copy sheet, the first limit switch is tripped by one of the saidlugs;

the second limit switch is tripped when that leading edge reaches thesecond of the bias shoes;

the third limit switch is tripped when the gripper reaches a positionwhich brings the trailing edge of the image area of the copy sheetbeneath the first bias shoe; and

the fourth limit switch is tripped when the trailing edge of the imagearea comes beneath the second bias shoe, and when the second of the twogrippers reaches a position which brings the the leading edge of theimage area of a copy sheet beneath the first of the two bias shoes, thefirst limit switch is tripped by the second of the said lugs, the secondlimit switch is tripped when that leading edge reaches the second of thebias shoes, the third limit switch is tripped when the gripper reaches aposition which brings the trailing edge of the image area of the copysheet beneath the first bias shoe, and the fourth limit switch istripped when the trailing edge of the image area comes beneath thesecond bias shoe; and

an electrical system connected between the limit switches and the biasshoes, which establishes an electrical connection between the first biasshoe and ground when the first limit switch is tripped, establishes anelectrical connection between the second bias shoe and ground when thesecond switch is tripped, breaks the said electrical connection betweenthe first bias shoe and ground when the third switch is tripped, andbreaks the said electrical connection between the second bias shoe andground when the fourth switch is tripped.

References Cited UNITED STATES PATENTS CHARLES A. WILLMUTH, PrimaryExaminer.

P. FELDMAN, Assistant Examiner.

1. A TONER UNIT ADAPTED FOR THE APPLICATION OF A POWDERED, SOLIDRESINOUS TONER TO AN ELECTROSTATIC IMAGE CARRIED BY A PHOTOELECTROSTATICCOATING ON A COPY SHEET WHICH COMPRISES IN COMBINATION: A STATIONARYCYLINDRICAL CORE OF A NON-MAGNETIC MATERIAL HAVING ITS AXIS INAPPROXIMATELY A HORIZONTAL POSITION, AND A PLURALITY OF LONGITUDINALGROOVES COUNTERSUNK IN ITS CYLINDRICAL SURFACE AT SPACED INTERVALSAROUND AT LEAST A SUBSTANTIAL PART OF ITS CIRCUMFERENCE; AN ELONGATED,CLOSELY FITTING STRIP OF A PERMANENTLY MAGNETIC MATERIAL POSITIONEDWITHIN EACH OF THE SAID GROOVES IN THE SURFACE OF THE STATIONARY CORE; AMEANS FOR ADJUSTING THE CIRCUMFERENTIAL POSITION OF THE SAID CYLINDRICALCORE AND FOR LOCKING IT IN ITS ADJUSTED POSITION, WHEREBY THE POSITIONSOF THE SAID MAGNETIC STRIPS WITH RESPECT TO THE UPPER HORIZONTAL TANGENTOF THE CIRCUMFERENCE OF THE SAID CORE CAN BE ACCURATELY ADJUSTED; AROTATABLE, HOLLOW CYLINDRICAL CORE OF A NON-MAGNETIC MATERIAL POSITIONEDAROUND THE STATIONARY CORE AND THE LONGITUDINAL MAGNETIC STRIPS CARRIEDIN ITS CYLINDRICAL SURFACE; A TRAY FOR RETAINING A BODY OF A TONER MIXIN CONTACT WITH THE LOWER PART OF THE SAID ROTATABLE CYLINDER; A MEANSFOR ROTATING THE SAID HOLLOW CYLINDER AROUND THE SAID STATIONARY CORE;AND A DOCTOR BLADE ADJACENT THE SAID ROTATABLE, HOLLOW CYLINDER,PARALLELING THE LENGTH OF THE SAID CYLINDER, SPACED AWAY FROM ITSSURFACE BY A UNIFORM DISTANCE ALONG ITS LENGTH, AND ADJACENT A LOCATIONAT WHICH THE SURFACE OF THE CYLINDER IS MOVED IN AN UPWARDLY DIRECTIONBY THE SAID MEANS FOR ROTATING IT AROUND THE STATIONARY CORE.